The rollout of the system for trains will begin on June 14 and run until March 2014. Initially, the trial will include the City Circle and stations to Bondi Junction, however, in the last quarter of 2013, it will be expanded to include stations on the North Shore line between Central and Chatswood.

In the first quarter of 2014 and subsequent to the trial, the next set of stations to be Opal-enabled will include those along the inner west from Redfern to Strathfield and north to Wyong on the Central Coast.

Following this, coverage will expand to cover stations along the western line out to Liverpool in the south west, Emu Plains in the west, and Richmond to the north west.

The remainder of the network will then be progressively made Opal-compatible.

"The rollout is complex and we are doing it in steps — we have learned from overseas that progressive rollouts work best and we expect there may be some hiccups along the way," the Minister for Transport Gladys Berejiklian said in a statement.

Benefits of the new technology include lower fares for commuters. After eight paid journeys (those where a customer correctly taps on and off) in one week, travel is free for the remainder of the week. The caps on pricing mean that this represents cheaper fares than existing equivalent weekly tickets.

A daily cap of $15 has also been introduced, where travel after this limit is reached is free. On Sundays, the daily cap is reduced to $2.50.

Specific to the train trial, an additional 30 percent discount on existing paper tickets will be applied for journeys outside of peak periods. At the moment, peak times are defined as 7am to 9am and 4pm to 6.30pm on weekdays.

The trial is currently only open to those who register their Opal cards. Although Transport for NSW has plans to allow commuters to travel on unregistered cards, and thus keep any personal information unlinked from their systems, this is not yet possible for the trial.

A similar trial for buses is scheduled for 2014 and the complete rollout of Opal across ferry, bus and train services is expected by 2015. No plans for a light rail trial have yet been announced, and no definitive date have been given by Transport for NSW as to when these services will be made Opal-compatible, but it is expected that they too will eventually make use of the same ticketing system.